A8 Transmission failure tracking
11-15-2017, 09:12 PM
#381
When they change the filter which they are supposed to do(they will because I went almost ballistic when they said there weren't any anywhere, Should have one today so Monday is me. One question since we have to drive 2-300 miles when finished think it will help if I run thru the gears a lot and drive fast as hell
11-16-2017, 08:49 AM
#383
Instructor
Replaced Differential
Hey Guys
The service dept. at Terry Labonte Chevrolet did a great job. They called me on Friday last week and said the new differential was here from GM and advised me to drop off my car on Tuesday to have it replaced. I left my car there Tuesday morning and they were kind enough to give me a loaner for couple days at no charge. Called me on Wednesday around lunchtime and said everything was fixed. I picked up my baby yesterday and it runs great. No rumble or warble anymore. The service tech guy told me they found metal particles in the differential fluid and it was a bearing that had failed. Hopefully this will be the solution.There were two more problems that was associated with the differential also taken care of. These were related to the stabilitrak and ABS. I will post a copy of the report later which may be helpful to other people going through the same issues.
The service dept. at Terry Labonte Chevrolet did a great job. They called me on Friday last week and said the new differential was here from GM and advised me to drop off my car on Tuesday to have it replaced. I left my car there Tuesday morning and they were kind enough to give me a loaner for couple days at no charge. Called me on Wednesday around lunchtime and said everything was fixed. I picked up my baby yesterday and it runs great. No rumble or warble anymore. The service tech guy told me they found metal particles in the differential fluid and it was a bearing that had failed. Hopefully this will be the solution.There were two more problems that was associated with the differential also taken care of. These were related to the stabilitrak and ABS. I will post a copy of the report later which may be helpful to other people going through the same issues.
Last edited by arvindnc; 11-16-2017 at 01:19 PM. Reason: update
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11-20-2017, 02:58 PM
#384
Burning Brakes
RPM Surge +/- 100-150
I haven’t been on the forum in about six months. What is the latest on why this is happening to our vehicles? Is this one of the symptoms of needing a new torque converter?
11-20-2017, 03:16 PM
#385
https://youtu.be/3I2IFsw37hc
Standard definition
http://www.youtube.com/watch?v=T-WlBlC9wNo
High definition
I haven’t been on the forum in about six months. What is the latest on why this is happening to our vehicles? Is this one of the symptoms of needing a new torque converter?
Standard definition
http://www.youtube.com/watch?v=T-WlBlC9wNo
High definition
I haven’t been on the forum in about six months. What is the latest on why this is happening to our vehicles? Is this one of the symptoms of needing a new torque converter?
Heidi
Save the Wave
11-20-2017, 10:00 PM
#386
Burning Brakes
Have you experienced a shutter yet? In our '15 A8 the car did this 100 to 200 RPM fluctuation for approx. 7K miles in cruise @ 47 miles, V4 mode before the shutter occurred. TC replacement was done after experiencing, not before. Had PDR video to show what was happening. In our '17GS all is still going well, but we are now at the crucial 8K miles on odometer; time will tell whether there has been an improvement .
Heidi
Save the Wave
Heidi
Save the Wave
11-20-2017, 10:34 PM
#387
Racer
Yes. Shudder is present. Car is at dealer. Brought car in this morning; the dealer told me it was normal and to go home. I came home and jumped on the forum and saw this thread. Brought the car back in the afternoon and left it. He called me at 5:30 and said the technician insists this is normal. I asked him how this could be since bulletin says no greater than 10 rpm surge. He didn't have a good answer and said he'd call me in the morning when the tech gets in. Don't know what else to tell him. Ideas?
If you can feel like your car is going over rumble strips when in V4 Mode, then this calls for the new fluid.
11-21-2017, 08:38 AM
#388
Check your oil pressure gauge when shutter occurs; In our '15 A8 the oil pressure went "nuts" during shudder ; Rapid fluctuation between 30 and 60 PSI.
Good luck; You may have to find another dealer/service Dept. to get your issue resolved. Make sure they have a certified Vette tech. and that this tech has done TC replacement. It's a big job and lots of things could go wrong in the tear down and replace work. Check out the pix on this forum what the car looks like during replacement of TC. Scary!!!! But a good Vette tech. can do the job right.
Heidi
Save the Wave
Good luck; You may have to find another dealer/service Dept. to get your issue resolved. Make sure they have a certified Vette tech. and that this tech has done TC replacement. It's a big job and lots of things could go wrong in the tear down and replace work. Check out the pix on this forum what the car looks like during replacement of TC. Scary!!!! But a good Vette tech. can do the job right.
Heidi
Save the Wave
11-21-2017, 02:09 PM
#389
Burning Brakes
https://youtu.be/3I2IFsw37hc
Standard definition
http://www.youtube.com/watch?v=T-WlBlC9wNo
High definition
I haven’t been on the forum in about six months. What is the latest on why this is happening to our vehicles? Is this one of the symptoms of needing a new torque converter?
Standard definition
http://www.youtube.com/watch?v=T-WlBlC9wNo
High definition
I haven’t been on the forum in about six months. What is the latest on why this is happening to our vehicles? Is this one of the symptoms of needing a new torque converter?
Really starting to unnerve me after reading about the others who are having more serious tc/tranny problems. Hard to enjoy something when you lose confidence in it.
11-21-2017, 02:26 PM
#390
My A8 2016 Stingray with 4.5 k miles exhibits the same exact behavior. Only occurs when in auto mode and 7th or 8th gear. Everything is buttery smooth. No shudder or anything. In fact, you wouldn’t know anything was going on if not observing the tach. Strangely, I also have a 2014 V8 Silverado with the A6 that does the same thing. Again, you’d not know if not looking at the tach. Can’t swx to manual paddles with it though.
Really starting to unnerve me after reading about the others who are having more serious tc/tranny problems. Hard to enjoy something when you lose confidence in it.
Really starting to unnerve me after reading about the others who are having more serious tc/tranny problems. Hard to enjoy something when you lose confidence in it.
I was planning on a GMC 1500 to replace my current 2500HD since it has a crew cab available with a 6.5 foot bed but rather than deal with AFM in another vehicle I will be buying another HD pickup with the diesel. The 1500 series pickup with the 6.2 looks like a nice setup but I am not buying another V8/AFM/8L90 product. My 2016 Z06 is doing fine with its Range module to avoid AFM but I really don't like having to use an aftermarket product just to avoid a designed in fault.
11-21-2017, 06:19 PM
#391
Racer
My A8 2016 Stingray with 4.5 k miles exhibits the same exact behavior. Only occurs when in auto mode and 7th or 8th gear. Everything is buttery smooth. No shudder or anything. In fact, you wouldn’t know anything was going on if not observing the tach. Strangely, I also have a 2014 V8 Silverado with the A6 that does the same thing. Again, you’d not know if not looking at the tach. Can’t swx to manual paddles with it though.
Really starting to unnerve me after reading about the others who are having more serious tc/tranny problems. Hard to enjoy something when you lose confidence in it.
Really starting to unnerve me after reading about the others who are having more serious tc/tranny problems. Hard to enjoy something when you lose confidence in it.
The following 2 users liked this post by GaryPitts:
jimmie jam (12-11-2017),
Squeaky Wheel (11-21-2017)
11-22-2017, 09:00 AM
#392
Burning Brakes
The fluctuation you see on the Tach as you probably know is engine fluctuation which is more evident in the rougher running V4 mode.
The plus/minus 10 RPM limitation that is in the service bulletin is a TCC
(Torque converter clutch slippage) limitation. This plus/minus 10RPM limitation is measured by the tech plugging his test equipment into the cars OBD port.
My 2015 base A8( built Aug 2014) had three transmission tear outs as the result of drive line issues and only on the last tear out in Feb of 2016 it did receive a new part # TC. That solved several of the drive line issues but there were other problems beyond the TC. My 2018 base A8 built June 2018 would have the most recent version of the transmission/TC and runs very well.
I think you will find on the forum many A8 owners reporting engine RPM fluctuations when steady state driving in V4 mode . Some have reported +/- 50 rpm , others a bit more and some a bit less. My understanding is the RPM fluctuations you are seeing on the tach ,unless there are other symptoms, are not necessarily an indication of a TC failure. From my own experience and that of others on the forum some of the symptoms of a TC failure are
* vibration/shudder felt in the car, like driving on rumble strips, when the car is in V4 mode, and it is very noticeable,
* harsh up shift from 1-2 first drive of the day
* harsh up shifts frequently felt in all gears
* harsh downshift felt on a rolling stop as the transmission downshifts from 3-1 slowing through about 3 or 4 MPH
If the only issue you have is the engine RPM fluctuation in V4 mode steady state driving you are probably O.K . Unless the dealer can diagnose a bad TC ( as per the service bulletins) you probably don't want the entire back end of your car torn out to replace the TC as when you get it back you are still going to see some amount of engine RPM fluctuation when steady state driving in V4 mode.
Good luck with the diagnosis and please post the results, good luck and hope your car is O.K
P.S In your post you indicated you had shudder. That would be sufficient for the dealer to apply the service bulletin procedures and test for a defective TC, IMHO.
The plus/minus 10 RPM limitation that is in the service bulletin is a TCC
(Torque converter clutch slippage) limitation. This plus/minus 10RPM limitation is measured by the tech plugging his test equipment into the cars OBD port.
My 2015 base A8( built Aug 2014) had three transmission tear outs as the result of drive line issues and only on the last tear out in Feb of 2016 it did receive a new part # TC. That solved several of the drive line issues but there were other problems beyond the TC. My 2018 base A8 built June 2018 would have the most recent version of the transmission/TC and runs very well.
I think you will find on the forum many A8 owners reporting engine RPM fluctuations when steady state driving in V4 mode . Some have reported +/- 50 rpm , others a bit more and some a bit less. My understanding is the RPM fluctuations you are seeing on the tach ,unless there are other symptoms, are not necessarily an indication of a TC failure. From my own experience and that of others on the forum some of the symptoms of a TC failure are
* vibration/shudder felt in the car, like driving on rumble strips, when the car is in V4 mode, and it is very noticeable,
* harsh up shift from 1-2 first drive of the day
* harsh up shifts frequently felt in all gears
* harsh downshift felt on a rolling stop as the transmission downshifts from 3-1 slowing through about 3 or 4 MPH
If the only issue you have is the engine RPM fluctuation in V4 mode steady state driving you are probably O.K . Unless the dealer can diagnose a bad TC ( as per the service bulletins) you probably don't want the entire back end of your car torn out to replace the TC as when you get it back you are still going to see some amount of engine RPM fluctuation when steady state driving in V4 mode.
Good luck with the diagnosis and please post the results, good luck and hope your car is O.K
P.S In your post you indicated you had shudder. That would be sufficient for the dealer to apply the service bulletin procedures and test for a defective TC, IMHO.
11-22-2017, 09:08 AM
#393
If you don't mind, when you do get your car back would you please post the part # of the "off" TC and the "ON" TC. Many of us who have had these issues are trying to keep track of what version TC is current.
Thanks and good luck.
P.S You are also going to get a new type of Transmission Fluid that became available about last Jan or Feb. It's really hard to get info on it but my understanding is that it is now a full synthetic made by Mobil 1 and has properties that better suits the cycling of the clutch pack, TCC ( Torque converter clutch apply) when operating in V4 mode
Last edited by 767guy; 11-22-2017 at 09:12 AM. Reason: added P.S
11-22-2017, 10:40 PM
#394
Intermediate
The fluctuation you see on the Tach as you probably know is engine fluctuation which is more evident in the rougher running V4 mode.
The plus/minus 10 RPM limitation that is in the service bulletin is a TCC
(Torque converter clutch slippage) limitation. This plus/minus 10RPM limitation is measured by the tech plugging his test equipment into the cars OBD port.
My 2015 base A8( built Aug 2014) had three transmission tear outs as the result of drive line issues and only on the last tear out in Feb of 2016 it did receive a new part # TC. That solved several of the drive line issues but there were other problems beyond the TC. My 2018 base A8 built June 2018 would have the most recent version of the transmission/TC and runs very well.
I think you will find on the forum many A8 owners reporting engine RPM fluctuations when steady state driving in V4 mode . Some have reported +/- 50 rpm , others a bit more and some a bit less. My understanding is the RPM fluctuations you are seeing on the tach ,unless there are other symptoms, are not necessarily an indication of a TC failure. From my own experience and that of others on the forum some of the symptoms of a TC failure are
* vibration/shudder felt in the car, like driving on rumble strips, when the car is in V4 mode, and it is very noticeable,
* harsh up shift from 1-2 first drive of the day
* harsh up shifts frequently felt in all gears
* harsh downshift felt on a rolling stop as the transmission downshifts from 3-1 slowing through about 3 or 4 MPH
If the only issue you have is the engine RPM fluctuation in V4 mode steady state driving you are probably O.K . Unless the dealer can diagnose a bad TC ( as per the service bulletins) you probably don't want the entire back end of your car torn out to replace the TC as when you get it back you are still going to see some amount of engine RPM fluctuation when steady state driving in V4 mode.
Good luck with the diagnosis and please post the results, good luck and hope your car is O.K
P.S In your post you indicated you had shudder. That would be sufficient for the dealer to apply the service bulletin procedures and test for a defective TC, IMHO.
The plus/minus 10 RPM limitation that is in the service bulletin is a TCC
(Torque converter clutch slippage) limitation. This plus/minus 10RPM limitation is measured by the tech plugging his test equipment into the cars OBD port.
My 2015 base A8( built Aug 2014) had three transmission tear outs as the result of drive line issues and only on the last tear out in Feb of 2016 it did receive a new part # TC. That solved several of the drive line issues but there were other problems beyond the TC. My 2018 base A8 built June 2018 would have the most recent version of the transmission/TC and runs very well.
I think you will find on the forum many A8 owners reporting engine RPM fluctuations when steady state driving in V4 mode . Some have reported +/- 50 rpm , others a bit more and some a bit less. My understanding is the RPM fluctuations you are seeing on the tach ,unless there are other symptoms, are not necessarily an indication of a TC failure. From my own experience and that of others on the forum some of the symptoms of a TC failure are
* vibration/shudder felt in the car, like driving on rumble strips, when the car is in V4 mode, and it is very noticeable,
* harsh up shift from 1-2 first drive of the day
* harsh up shifts frequently felt in all gears
* harsh downshift felt on a rolling stop as the transmission downshifts from 3-1 slowing through about 3 or 4 MPH
If the only issue you have is the engine RPM fluctuation in V4 mode steady state driving you are probably O.K . Unless the dealer can diagnose a bad TC ( as per the service bulletins) you probably don't want the entire back end of your car torn out to replace the TC as when you get it back you are still going to see some amount of engine RPM fluctuation when steady state driving in V4 mode.
Good luck with the diagnosis and please post the results, good luck and hope your car is O.K
P.S In your post you indicated you had shudder. That would be sufficient for the dealer to apply the service bulletin procedures and test for a defective TC, IMHO.
12-11-2017, 10:35 AM
#396
Le Mans Master
Member Since: Nov 2015
Location: Lake Havasu City Arizona
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12-11-2017, 11:32 AM
#397
Just my opinion based on past experience with automatic transmission.
Locking torqu convertors that are starting to fail will shudder and hunt. With this v4 to v8 feature going back and fourth it sounds like the perfect storm for causing the TC to constantly be locking, unlocking, locking unlocking and so on. This is wearing them (the C7 autos) out IMO.
If I had a auto, I'd search for a bullet proof NON-locking spragged TC from some reputable vendor out there. I went through 4 TC's with a high horsepower turbo car. When I went to NON-locking convertor it was a beautiful thing. I didn't miss that few hundred RPM that the locking gave in gas mileage. With 8 gears, what is locking the convertor saving in gas mileage anyway? Go 2800 RPM stall speed too, still driver friendly and not slushy like old technology.
Locking torqu convertors that are starting to fail will shudder and hunt. With this v4 to v8 feature going back and fourth it sounds like the perfect storm for causing the TC to constantly be locking, unlocking, locking unlocking and so on. This is wearing them (the C7 autos) out IMO.
If I had a auto, I'd search for a bullet proof NON-locking spragged TC from some reputable vendor out there. I went through 4 TC's with a high horsepower turbo car. When I went to NON-locking convertor it was a beautiful thing. I didn't miss that few hundred RPM that the locking gave in gas mileage. With 8 gears, what is locking the convertor saving in gas mileage anyway? Go 2800 RPM stall speed too, still driver friendly and not slushy like old technology.
12-11-2017, 05:48 PM
#398
The simple solution to the AFM modulated lockup clutch problem is either a Range module or select manual mode; either will prevent the ECM from commanding V4 mode with the resultant lockup clutch modulation.
The lockup clutch function in the 8L90 works fine when it is operating as a normal automatic transmission not being abused by GM's poorly implemented AFM system.
I haven't been following the new ZR1 closely but did it manage to escape this silly system? I am pretty sure I recall one of our European members saying automatic equipped C7 models designed for the EU market only go into V4 mode in the eco setting just like M7 models which would be nice.
The lockup clutch function in the 8L90 works fine when it is operating as a normal automatic transmission not being abused by GM's poorly implemented AFM system.
I haven't been following the new ZR1 closely but did it manage to escape this silly system? I am pretty sure I recall one of our European members saying automatic equipped C7 models designed for the EU market only go into V4 mode in the eco setting just like M7 models which would be nice.
12-12-2017, 08:04 AM
#399
Burning Brakes
Well, the good news is you will find when you get your paper work that the part # of the TC going on is different than the TC that is coming off....at least that is something !
If you don't mind, when you do get your car back would you please post the part # of the "off" TC and the "ON" TC. Many of us who have had these issues are trying to keep track of what version TC is current.
Thanks and good luck.
P.S You are also going to get a new type of Transmission Fluid that became available about last Jan or Feb. It's really hard to get info on it but my understanding is that it is now a full synthetic made by Mobil 1 and has properties that better suits the cycling of the clutch pack, TCC ( Torque converter clutch apply) when operating in V4 mode
If you don't mind, when you do get your car back would you please post the part # of the "off" TC and the "ON" TC. Many of us who have had these issues are trying to keep track of what version TC is current.
Thanks and good luck.
P.S You are also going to get a new type of Transmission Fluid that became available about last Jan or Feb. It's really hard to get info on it but my understanding is that it is now a full synthetic made by Mobil 1 and has properties that better suits the cycling of the clutch pack, TCC ( Torque converter clutch apply) when operating in V4 mode
On the bright side, I got a free multi point vehicle inspection. (Read: Free dealer provided burnouts in the back parking lot at no cost to the customer.)
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767guy (12-12-2017)
12-13-2017, 03:24 PM
#400
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Member Since: Jun 2016
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I've had issues with my 2015 corvette stingray since i got it at 19200 miles. Started out with the reverse gear having a delay when i put it in gear. had dealer change out parts and it stopped for a few weeks then started with the drive gear. Has a delay and gives a hard jerk at times going into drive. have called and emailed GM several times but they say this is normal of the car. Just wanted to know if anyone else had this issue and has anything been done to correct the issue. This is becoming a problem.